U.S. Pat. No. 3,319,202 to Lockie discloses a cooling system for partially buried transformers. The system includes baffles intermediate of the transformer and the transformer enclosure. The baffles form two concentric air spaces between the transformer and the enclosure such that the baffles substantially retain radiant energy within the air space between the baffles and the transformer. Ambient air is drawn into the apparatus between the barrier and the enclosure wall and subsequently passes between the baffle and the transformer to exit the housing.
U.S. Pat. No. 3,420,943 to Short disclosed a ventilator for underground electronic equipment. Short employs a tortuous air intake for directing ventilating air downward in the underground chamber such that the air subsequently rises past the transformer and exits through an above ground stack.
U.S. Pat. No. 3,443,157 to Uptegraff, Jr. discloses an electrical transformer disposed underground for direct dissipation. The transformer unit includes an elongated heat conductive tank in a sealed chamber in which the electronic components are housed.
U.S. Pat. No. 3,452,813 to Watkins et al. discloses an electric cable installation wherein ambient air is drawn into the installation and directed across a heat exchanger wherein the heated air is then expelled from the chamber.
Many devices of the prior art, either draw ambient air into an above ground or underground housing. The air is drawn over the electronics and discharged to the atmosphere. Although the use of ambient air provides a limitless supply of fluid for cooling the system, introduction of ambient creates substantial problems.
Ambient air usually includes a moisture or water content. Under certain conditions, the moisture may condense out of the ambient air onto the electronic components and the inside of the housing. In addition, the direct entry of a continuous flow of ambient air requires complicated gates or passages to prevent unintended intrusion of foreign objects into the air ducts.
Prior art devices have also completely buried the electronic components underground. However, such buried substantially hinder access to the components for repair or maintenance.